Laptop won't turn on

I have a Sony PCG-7D2L laptop that will no longer power up.  When you hit the power button, absolutely nothing lights up, spins, or makes any noise whatsoever.  I have verified that it is getting 19.5 volts coming in to the board.  I have also taken it apart and tested the voltage coming into the motherboard and it is 19.5v as well.  

Note that the Sony laptop doesn't have the usual jack soldered directly onto the motherboard, but rather, it has a little cable extender from the jack that travels to the middle of the motherboard.  

I have taken out the battery, memory, hard drive, and DVD to rule out any interference, although that shouldn't have had anything to do with it.   It still doesn't start.

Is there anything else it could be other than the motherboard?  
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rg20Connect With a Mentor Commented:
To ensure the powersupply is good, you can test something past that point.
Put your volt meter to the hard drive connector and see if your getting any voltage there, or even the CPU fan.

If you don't get voltage beyond the power supply you have a power supply issue.

There should be somewhere on the board where that 19 v is regulated down to 12 then down to 5 or 3.5 for the CPU
Perhaps the button for turning it on doesn't work (did you try turning it on while you had the laptop open? Another issue that can cause such a problem is the switch that checks if the lid is open or closed always sees it as closed.
B1izzardAuthor Commented:
I put the tester where the battery connects and it was showing 4.5v.  I tried putting it on the 3 pins where the CPU fan is, but wasn't getting any voltage no matter which 2 of the 3 pins I touched with the tester.
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rindiConnect With a Mentor Commented:
You'd only get voltage there if the PC was running, and even then not at all times, as the PC only turns the fan on when the CPU gets hot enough.
nobusConnect With a Mentor Commented:
here my laptop troubleshooting guide :
- if no display - test with an external monitor
- test also with a known good battery !
- remove battery and AC adaptor, hold power button for 20 sec, connect AC and reboot --> any display ? if NO -->
- disconnect all disk and cd drives, battery , and other cards and peripherals, leave only 1 ram stick
- boot -->any display ?
- if NO remove all ram and reboot --> if NO beeps, mobo or cpu bad ; if it beeps, replace ram stick
-if you can access the bios battery, remove the battery, AC, and bios battery for a minute to reset the bios
or test it, it should read 3 V
*** you can test the disk on another pc, if you like !

for troubleshooting the display (LCD) problems :      LCD troubleshooting
asiduConnect With a Mentor Commented:
>>I have taken out the battery, memory, hard drive, and DVD to rule out any interference, although that shouldn't have had anything to do with it.   It still doesn't start.<<

Do you get any beeps when you apply power ?
If yes its an indication that the CPU is trying to perform the start up process.

Also confirm if your  power adapter works fine. If you have another good working adapter I would use it for testing.
You could also test system with a good charged battery.

Just ensure your adapter output has enough current to run the machine. Clean the fan and CPU thermal cooling fins is there is dust sticking on it.

If the input is good, its likely that the CPU or motherboard is bad.
B1izzardAuthor Commented:
It is getting through to the motherboard with 19.5v.  No beeps.  I'm going to replace the motherboard.  
Sony usually suffer at the graphic card, does it have such an issue.

please save my articles here all experts exchange home testing your ac power adapter and testing in repairing york dc power jack
just click on the link laptops and notebooks next click on the article tab
B1izzardAuthor Commented:
Replaced motherboard and it is now working perfectly.  Thanks for the advice all.
have fun..
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